Big game hunter Corey Knowlton's long wait to kill an endangered black rhinoceros in Africa is finally over.

In a decision Thursday that's certain to rile animal rights activists, the U.S. Fish and Wildlife Service removed the last hurdle in the way of Knowlton's quest. More than a year after the wealthy Texan submitted the winning $350,000 bid for a Namibian government permit at a Dallas auction to shoot the animal, the agency announced that it approved his application for a separate U.S. permit to import the animal's carcass back home as a trophy.

As soon as Knowlton verifies that funds sitting in an escrow account have been wired to Namibia, a Fish and Wildlife official said, the permit is his.

The agency explained its controversial decision by saying hunting rhino bulls such as the one Namibia selected for Knowlton is a necessary evil to increase the population of a species in peril. Older rhinoceros bulls are known to keep younger bulls from mating with cows in their groups even after the elder males can no longer reproduce. After studying Namibia's conservation program, the agency deemed that culling certain bulls "will benefit ... the species," according to a statement released as part of the announcement.

American hunters pay handsomely for a chance to track and kill big game throughout Africa, and the money is placed in a fund that helps impoverished nations such as Namibia afford efforts to protect the rhinoceros from a wave of poaching that has reduced the population to a critical low. The money also helps pay officials who manage wildlife reserves.

The service also approved a second trophy request from Michael Luzich, a Las Vegas investor and hunter who shot a rhinoceros last year after a purchasing a permit for $200,000 from Namibian officials. Luzich shot a rhino bull after paying for the privilege in 2013 and will receive a permit in 10 days, an agency official said.

“United States citizens make up a disproportionately large share of foreign hunters who book trophy hunts in Africa,” said Daniel Ashe, Fish and Wildlife's director. “That gives us a powerful tool to support countries that are managing wildlife populations in a sustainable manner and incentivize others to strengthen their conservation and management programs.”

Not every nation gets the favorable nod extended to Namibia, Ashe said. As part of its announcement Thursday, Fish and Wildlife also said it would deny all requests to import the remains of elephants sport-hunted in Zimbabwe after 2013. The agency said it "is not assured that the benefits of sport hunting will be realized" in Zimbabwe because the information that country shares about the management of its herd is incomplete.

African elephant populations are carefully watched by U.S. and United Nations officials after being reduced by more than half in the past 30 years. The species is listed as threatened by the International Union for the Conservation of Nature (IUCN).

But the black rhinoceros is in far more trouble; fewer than 5,000 African black rhinos remain in the wild. There were 70,000 at the start of the 1960s before a wave of hunting and poaching dramatically lowered their numbers. An international crackdown stopped poaching for a while, but it resumed several years ago when black-market prices for rhino horn in China and Vietnam, where it is valued as ornaments and traditional medicine, reached $45,000 per pound.

A ranger walks behind a pair of black rhinoceros at the Imire Rhino and Wildlife Conservation Park near Marondera, Zimbabwe. (Philimon Bulawayo/Reuters)

Knowlton's public bid at an auction sponsored by the Dallas Safari Club in that city's convention center last year touched off a furor among animal rights advocates. At the height of the backlash, both Knowlton and the club's managers claimed they received death threats, and the FBI investigated.

Fish and Wildlife Service usually receives no more than eight public comments on applications for permits to import international hunting trophies. Knowlton’s and Luzich's applications drew 15,000 e-mails and 135,000 signatures on a petition. The approvals of their application will mark the second and third time the U.S. has allowed black rhinoceros hunting trophies in 30 years. Last year, Fish and Wildlife approved the first permit to import a rhino horn trophy in more than three decades, according to a statement on the agency's Web site.

Jeff Flocken, the North American regional director of the International Fund for Animal Welfare, condemned Fish and Wildlife's decision Thursday. "We are disappointed in the news today that the U.S. Fish and Wildlife Service has chosen to allow the importation of black rhinos hunted for sport," he said. The agency's approval will only inspire other hunters to kill animals on the verge of extinction, Flocken said. "The real value and worth of the species — and all critically endangered species for that matter — should be in their life, not the price tag for their death."

The director of the Humane Society International's wildlife department, Teresa Tellecky, called the decision a disaster. "Twelve hundred rhinos were poached last year in South Africa alone," she said. She said the U.S. is telling Vietnamese that rhino horn doesn't work as traditional medicine but allowing hunters to import their heads with the horns.

Telecky said the society has investigated whether money provided by hunters to Namibia used for conservation and found no information to prove or disprove that it does. It goes into an account called the Game Products Trust Fund that can be used for a number of projects, including agriculture and rural development.

But conservationists organizations are split on the issue. The Iternational Union for the Conservation of Nature, which uses data from a variety of government sources to survey the status of animals on land and in the oceans, supports carefully managed hunts of rhinoceros bulls in Namibia and South Africa, saying their populations have increased slightly with the help of those conservation measures.

The IUCN has studied and endorsed Namibia's conservation program, and Fish and Wildlife officials said their positive findings factored into their own analysis of Namibia's management.

While the IUCN supported Knowlton, activists such as Flocken called the hunters throwbacks to another age when key species were tracked and killed for sport throughout the world. A Facebook page to "Stop Corey Knowlton From Killing Black Rhino" pictured him as the devil and drew 600 likes.

Knowlton did not answer an e-mail request for an interview Thursday. But in a telephone interview with The Washington Post in January, he said the anger generated by his bid shocked him. Still, Knowlton said, he doesn’t regret participating in the auction, and the goal of the hunt is conservation. “This wasn’t my plan, but the plan of the Namibia Environment and Tourism [Ministry],” he said. “They understand I wasn’t this evil guy who was hell-bent on killing something.”

At that time, Knowlton said his decision to hunt the animal or have his money returned by Namibia hinged on whether Fish and Wildlife approved his request to bring home a trophy. "It's hard to say why hunters value the remains so much -- respect, a memorial, the time you had with it," Knowlton said. "I believe it's all of that. A hunter’s relationship with wildlife is intimate.”

If he doesn't shoot the rhinoceros bull, Knowlton said, someone else will. “There’s a group of rhinos" the Namibians want killed, and since the permit was granted, “a number of rhinos have been killed by other rhinos.”

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